1. Field of the Invention
The invention relates generally to a method of forming an insulating film in a semiconductor device. More particularly, the invention relates to a method of forming an insulating film in a semiconductor device by which a low-dielectric insulating film that will be applied to the nano technology in the deposition equipment including the existing PECVD (plasma enhanced chemical vapor deposition) equipment.
2. Description of the Prior Art
As the level of integration in the semiconductor device is increased, a metal line is formed in multiple layers. In order to electrically insulate these lines, an inter-metal line insulating film is formed between the metal line layers. The dielectric constant of the inter-metal line insulating film is changed depending on the type of materials. The performance of the device is dependent on the dielectric constant. In other words, the inter-line insulating film is formed between the upper line and the lower line. The semiconductor device has the same structure to the capacitor. With this structure, the parasitic capacitor is formed and the parasitic capacitor degrades the operating speed of the device. As a result, in order to minimize electrical characteristics of the device affected by the parasitic capacitor, it is required that the dielectric constant be lowered by lowering the inter-line insulating film using a thin low-dielectric film.
In the manufacture process of the semiconductor device, a method of forming the inter-line insulating film having a low dielectric constant includes one by which hydrocarbon (CH3) of a silica network structure is doped in order to increase porosity. However, if the concentration of hydrocarbon is increased, it is difficult to lower the dielectric constant below 2.7 since thermal stability and mechanical strength of the film are degraded.
Meanwhile, if the low-dielectric insulating film is formed by means of a conventional spin-on method, there are drawbacks that it is difficult to control the fine structure of the film and the mechanical strength of the film is weak compared to the CVD method.